Hydrotreating of petroleum residuum using shaped catalyst particles of small diameter pores

ABSTRACT

Shaped catalyst particles having a polylobal cross-section are utilized in hydrotreating a petroleum residuum to obtain a desulfurized product. The catalyst particles have a surface area greater than 150 m2/g and a catalyst pore volume of 0.35-0.85 cc/g resulting from a major portion of pores of diameters in the range 40-90A.

This is a division of application Ser. No. 508,780, filed Sept. 24,1974, now U.S. Pat. No. 3,966,644 which is a continuation-in-partapplication of Ser. No. 385,519, filed Aug. 3, 1973, now abandonedwhich, in turn, is a continuation-in-part of Ser. No. 255,491, filed May22, 1972, and now abandoned.

This invention relates to small porous catalyst particles havingspecific shape and pore characteristics and advantageous utility inhydrotreating petroleum residuum. More particularly, the inventionrelates to such particles that have concave cross-sectional shapecharacteristics and a pore volume constituted of a major portion ofsmall-diameter pores. The invention also relates to aresiduum-hydrotreating process employing the catalyst particles.

In the past, catalyst particles were generally of spherical orcylindrical shape. Such shape characteristics were convex in nature andsuch particles provided desirable activity for the specifichydrotreating processes in which they were customarily employed. Sincethe particles also had desirable physical properties and were readilyprepared, little interest was shown in novel catalyst sizes and shapes.

Recent shortages in petroleum supplies coupled with increased demand forproducts thereof have necessitated reliance on secondary sources inincreasing amounts. These secondary sources require more extensivehydrotreating and are more difficult to process. Use of conventionalspherical or cylindrical catalyst particles does not result in efficienthydrotreating of secondary petroleum sources, particularly residuum.Recourse, therefore, must be had to more effective catalysts and/orhydrotreating processes if the shortages are to be alleviated by resortto secondary petroleum sources.

It is known that increased catalyst activity results from reducedcatalyst particle size. It is also known that with conventional catalystshapes, a decrease in particle size results in an increase in pressuredrop across the catalyst bed. Accordingly, with respect to the tolerablepressure drops, there is a minimum particle size of catalyst particlesthat can be employed using conventional shapes. Large pressure dropsresult from close packing of the catalyst particles in the bed withsubstantial elimination of the void fraction of the bed.

It is known that the void fraction of catalyst beds can be increased byusing catalyst particles of irregular shapes so as to minimize closepacking of the particles. However, such use generally results in loss inbed efficiency because of the resulting lower volume of catalystparticles in a given volume of reactor space.

In U.S. Pat. No. 3,674,680 issued July 4, 1972 to Hoekstra et al., thereis disclosed a process for hydrotreating petroleum residuum by use ofsmall catalyst particles having both distinctive shape and a majority ofpores of a diameter of 100 to 200 Angstrom units. This patent is basedon the discovery that metallic contaminants present in the residsprocessed penetrate to a depth of 0.0085 inch from the particle surfaceand the presumption that reside molecules do not penetrate much further.Thus, an ideal catalyst, according to the patentees, would be one whichhas all points in the catalyst particle no greater than about 0.0085inch from the particle surface so as to eliminate any wasted catalystmaterial from the reactor. Such a catalyst particle would have aneffectiveness approaching 1.0 due to the elimination of unused or wastedcatalyst material. The patentees further point out that a cylinder ofone-sixteenth inch diameter has an effectiveness of only 55% that of theideal catalyst defined. The patentees teach that if the catalystparticle occupies only 70% to 90 % of the volume of the comparablecylinder and has a major portion of pores in the range of 100-200Angstrom units, small particles can be used without excessive pressuredrop and the metallic contaminates will be deposited in the catalystparticles up to a depth of about 0.0085 inch from any particle surface.

It is known that catalyst area containing deposited metalliccontaminants is inactivated by said contaminates. Accordingly, for thecatalyst of Hoekstra, et al. to remain active after deposition of themetallic contaminants it must contain additional catalytic area toprovide activity. This active area can only exist within the catalystparticles at a depth greater than about 0.0085 inch from any particlesurface. Although this inner space is considered wasted in the initialcatalyst because it is at a depth greater than 0.0085 inch from anyparticle surface, it is evident that the space at a depth less than0.0085 inch from any particle surface is wasted because of inactivationby the presence of metallic contaminants therein and that the innerspace, initially considered wasted, can be the only active catalystspace for continuing hydrotreating reaction after metallic contaminationoccurs. Accordingly, although the small-size catalyst particles ofHoekstra et al. are shaped so as to minimize pressure drop, the largepores provide for deposition of contaminants, and relatively smallinaccessible catalyst sections remain. As a result, the catalystparticles of Hockstra et al. do not provide improved activity activityover catalyst particles of conventional shape.

In U.S. Pat. No. 3,509,044, issued Apr. 28, 1970 to C. E. Adams et al.,it is shown that the use of catalyst particles having a major portion ofpores of diameter in the range of 30-70 Angstrom units in thehydrotreating of residuum results in a longer service life of saidcatalyst particles than that of catalyst particles of other porediameters. However, ever, Adams et al. do not teach small particles ofspecial shape and do not provide catalyst particles having improvedactivity during service use over conventional catalyst.

In accordance with the present invention, there is provided a poroushydrotreating catalyst particle having a composition of a major portionof alumina; up to about 36 weight percent of silica, based on the totalweight of silica and alumina; from about 10 to 25 weight percent ofmolybdenum in the form of its oxide or sulfide; and a total of about 1to 8 weight percent of a metal selected from cobalt, nickel and mixturesthereof in the form of the corresponding oxide or sulfide, saidpercentages being based on the total weight of said catalyst particle:said particle being further characterized by a concave cross-sectionalbase extending over a length to define a concave geometric solid saidsolid being characterized by a concavity index greater than 1.0; a voidfraction in the range of about 0.25 to 0.60; a particle size defined bya ratio of geometric volume to geometric surface in the range of about0.001 to 0.042 inch; a catalytic surface area greater than about 150square meters per gram; and a catalytic pore volume in the range ofabout 0.35 to 0.85 cubic centimeters per gram, said catalytic porevolume resulting from a major portion of pores of diameter in the rangeof about 40 to 90 Angstrom units when measured with mercury at up to50,000 pounds per square inch absolute pressure and a contact angle of140°.

In preferred embodiments of the present invention, there is provided aporous hydrotreating catalyst particle having a composition of a majorportion of a alumina; up to about 36 weight percent of silica, based onthe total weight of silica and alumina; from about 10 to 25 weightpercent of molybdenum in the form of its oxide or sulfide; and a totalof about 1 to 8 weight percent of metal selected from cobalt nickel andmixtures thereof in the form of the corresponding oxide or sulfide, saidpercentages being based on the total weight of said catalyst particle:said particle being further characterized by a trilobal cross-sectionalbase extending over a length to define a concave geometric solid, saidsolid being characterized by a concavity index in the range of 1.05 to1.45; a void fraction in the range of about 0.35 to 0.50; a particlesize defined by a ratio of geometric volume to geometric surface in therange of about 0.005 to 0.025 inch; a catalytic surface area greaterthan 200 square meters per gram; and a catalytic pore volume in therange of about 0.35 to 0.85 cubic centimeters per gram, said catalyticpore volume resulting from a major portion of the pores of diameter inthe range of about 40 to 90 Angstrom units when measured with mercury atup to about 50,000 pounds per square inch absolute pressure and acontact angle of 140°; said trilobal cross-sectional base being suchthat the lobes are defined by circles having centers and equaldiameters, the centers of which circles are spaced from each other sothat lines joining said centers form an equilateral triangle, the sidesof which are of a dimension which is from about 3/8 to about equal thatof the circle diameters and all cross-sectional base included by saidcircles and triangle is of said catalyst composition.

In accordance with the process aspect of the present invention, there isprovided a process for hydrotreating a petroleum residuum with theshaped, porous catalyst as described above, which process comprisescontacting said residuum with the catalyst particle in the presence ofhydrogen at a flow rate of about 500 to 5,000 standard cubic feet perbarrel of oil at a liquid hourly space velocity of about 0.10 to 5.0reciprocal hour, a temperature in the range of about 600 to 850° F., anda total pressure in the range of about 200 to 10,000 pounds per squareinch gauge.

Unexpectedly, the catalyst particles of the present invention are higherin activity in hydrotreating residuum and maintain higher activity forlonger times of service than do comparable catalyst particles of theprior art of similar size. In addition, the catalyst particles of thepresent invention possess greater crush strength and attritionresistance than do comparable catalyst particles of the prior art.

In order that the size and shape characteristics of the catalystparticle of the present invention may be clearly understood, thefollowing discussion is given.

GENERAL NATURE

A cylinder may be defined as a solid of uniform cross-section which maybe generated by a straight line moving round a closed curve andremaining parallel to the axis. What is generally understood by the wordis a right circular cylinder for which the closed curve is a circlewhose plane is perpendicular to the axis of the cylinder.

The catalyst particle of the present invention differs from the rightcircular cylinder only in that the closed curve is not circle but isconcave closed curve. A concave closed curve is one such that two pointswithin or on the edges of the curve can be joined by a straight linewhich does not lie wholly within the closed curve. Typical closed curvesof the catalyst particles of the present invention are ring shape or ofvarious forms of polylobal shapes. Thus, in the present invention, thecatalyst particle has a concave cross-sectional base, which base isperpendicular to the axis of the solid and extends for a sufficientlength to provide the solid particle. The cross-sectional base of thecatalyst particles of the present invention has a area less than that ofa 1/8 inch diameter circle and the ratio of the particle length to itsnominal diameter is generally from about 2:1 to about 5:1. The actualsize relationships of the particles of the invention are more accuratelygiven by the ratio of geometric volume to geometric surface, which willbe discussed hereinbelow.

When the cross-sectional base is polylobal, which represents thepreferred embodiment, the lobes of the base arise from circles of equaldiameter and are connected so as to form a closed curve. The centers ofthe circles making up the lobes may be spaced at various distances fromone another, depending upon the nature of the polylobal shape desired.In one embodiment, the circle centers may be spaced more than a diameterapart and the space between the circular lobes if filled with thecatalyst composition of the lobes to a thickness which is at least equalto a circle radius. The spacing of the circle centers in such embodimentmay be up to about 21/2 circle diameters. In an alternative embodiment,the circle centers are spaced from about 3/8 to 1 circle diameter apartand all space between the lobes is filled with he catalyst compositionof the lobes to a thickness which is at least equal to a circle radius.In this alternative embodiment, at many spacing distances sufficientoverlapping of the circular lobes will occur so as to provide thenecessary thickness of catalyst composition between lobes.

In a more preferred embodiment, the cross-sectional base will consist ofthree or more lobes of circles of equal diameter, the centers of whichcircles are spaced from each other by a distance which is from about 3/8to about 15/16 of a circle diameter and lines joining the circle centersform a regular polygon, each side of which is equal in length to thespacing distance of the circle centers and all area occupied by thelobes and polygon is of the catalyst composition. A greatly preferredpolylobal cross-sectional base in one of three lobes of circles of equaldiameter, the centers of which circles are spaced so as to form anequilateral triangle each side of which is about 15/16 of a circlediameter.

The catalyst particles of the present invention are prepared by amolding technique, such as by extrusion. The molded particle is alsosubjeced to calcination, during which a shrinkage in dimensions of 25%or more may occur. Due allowance, of course is necessary to providefinished catalyst particles of the size desired. The shrinkage may alsocause some distortion from the desired shape, i.e. the final particlesmay depart somewhat from the desired idealized shapes. However, theextent to which distortion occurs does not adversely affect catalystproperties and the definition of the catalyst shape is in terms of theidealized dimensions although it is recognized that some distortions mayoccur.

CONCAVITY INDEX

A geometric solid is convex if all pairs of points lying within or onthe cross-sectional surface of the solid can be connected by a straightline which is completely contained within or on the surface thereof.Conversely, a geometric solid is concave is pairs of points lying withinor on the cross-sectional surface of the surface of the solid can beconnected with a straight line which is not completely contained withinor on the surface of the solid. The geometric volume of a convex solidof the minimum size necessary to contain a concave solid will be greaterthan the geometric volume of the concave solid. Letting V_(x) equal thevolume of the minimum convex solid specified and V_(c) equal the volumeof the contained concave solid, the Concavity Index C, is is given bythe expression:

    C=  V.sub.x /V.sub.c

In order for the geometric solid to be concave, the value of ConcavityIndex must be greater than 1.0 and preferably is about 1.10 t 1.45

VOID FRACTION

The void fraction represents the closeness of particle packing that canbe obtained with particles of a given shape. In a given geometric volumeof space, a specific number of catalyst particles can be packed.Multiplying the geometric volume of the particle by the number ofparticles, a total geometric particle volume, V_(p), is obtained. If theapparent geometric volume is space packed is V_(s), there will existvoid space V_(v), not actually occupied by catalyst particles Thus,V_(s) =V_(p) +V_(v). The Void Fraction, E, associated with a given shapeis given by the expression:

    E=Vv/Vs=Vv/Vv+Vp

In order for a catalyst particle to be useful, in accordance with thepresent invention, it must have a void fraction in the range of about0.25 to 0.60, preferably between about 0.35 and 0.50.

RATIO OF GEOMETRIC VOLUME TO GEOMETRIC SURFACE

Catalyst particles of the present invention have a characteristicgeometric volume and geometric surface area associated therewith as aconsequence of their cross-sectional shape and length. The geometricvolume and geometric surface area are readily calculated fromappropriate measurements associated with the perfect geometric forms.Actual catalyst particles approximate such forms and their volumes andsurface areas can be closely estimated from the corresponding geometricmodels. The ratio of geometric volume to geometric surface area isindicative of particle size and should be in the range of about 0.001and 0.042 inch, preferably between about 0.005 and 0.025 inch.

In addition to the geometric considerations reflecting particle size andshape, it is also necessary for the catalyst particles to possesscertain characteristics that are associated with catalytic action. Thesecharacteristics and methods of measurement are next given.

CATALYTIC SURFACE AREA

The catalytic surface area is expressed in square meters per gram and isdetermined in accordance with the procedure described by H. W. Daecherand F. H. Stross in Anal. Chem., Vol. 34, page 1150, 1962. This valueshould be greater than about 150 square meters per gram, preferablygreater than 200 square meter per gram, and more preferably from about250 to 300 square meters per gram.

CATALYTIC PORE VOLUME

The catalytic pore volume of the catalyst represents internal cavitiestherein. Measurements are made by conventional procedure based onmercury penetration at up to 50,000 pounds per square inch absolutepressure using the contact angle of 140°. In this procedure, both totalpore volume and pore diameter are determined. Catalyst particles of thepresent invention will have a total pore volume in the range of about0.35 and 0.85 cubic centimeters per gram with the majority of the poreshaving a diameter in the range of about 40 to 90 Angstrom Units inaccordance with the method of determination specified.

In addition to the geometric size and shape relationships and thecatalytic characteristics, the catalyst particles will also have aspecific chemical composition, which is next discussed.

The catalyst particles will comprise a major portion of alumina and, inparticular, small-pore alumina so as to be consistent with the catalyticcharacteristics specified above. The alumina will thus be the majorstructure-forming component of the catalyst particles. In addition toalumina, the catalyst particles may contain up to about 36 weightpercent of silica, based on the total weight of silica and alumina. Theamount of silica added as such will generally be up to about 5 weightpercent, same basis. When added in the form of aluminosilicate, such aszeolite, it may be as high as about 45 weight percent of zeolite, thusgiving rise to about 36 weight percent of silica, as indicated.

The catalyst particles will also contain from about 10 to 20 weightpercent of molybdenum in the form of its oxide or sulfide and a total ofabout 1 to 8 weight percent of a metal selected from cobalt and nickeland mixtures thereof in the form of its oxide or sulfide. Theseconstituents serve as activator and promoter materials and are based onthe total weight of the catalyst particle. It is to be understood thatwhen both nickel and cobalt are present, their combined weight percentshould be in the range given.

In preparing the catalyst particles of the present invention,precipitated alumina is prepared in accordance with conventionalprocedures, well-known in the art. After filtration, washing andadjustment in composition as may be desired, the aqueous slurry isspray-dried in accordance with conventional procedures. The spray driedpowder may then be prepared as an extrusion mix, incorporating therein,if desired, the activator and promoter ingredients. Typically,mix-mulling is employed in providing the extrusion mix. The extrusionmix is then extruded through a die having orifices of the desiredcross-sectional shape and the extrudate is cut to the proper length toprovide the desired shape characteristics specified. The extrudate isthen subjected to drying and calcination in conformity with conventionalprocedures. If provision for activator and promoter incorporation wasnot made prior to extrusion, the calcined extrudate may be suitablytreated with activator and promotor materials and again calcined, inaccordance with conventional procedures. Advantageously, preparation ofcatalyst particles of the present invention requires no new processingsteps, but merely requires conventional processing directed to the novelcombination of geometric, catalytic and compositional features of thecatalyst particles as described.

In addition to extrusion, catalyst particles of the present inventionmay be prepared by other procedures. For example, the shaped articlescan be obtained by tabletizing or pelletizing, or molding, etc.

The catalyst particles prepared as described after preliminary sulfidingare useful in hydrotreating petroleum residuums. In hydrotreatingreactions, several effects are observed. Primarily, hydrodesulfurizationis accomplished. Hydrocracking, to a limited extent, nitrogen removaland aromatic saturation may also occur. Accordingly, hydrotreating isthe preferred term used to describe the catalytic reaction effectedsince it is generic as to the effects observed.

In carrying out the process of the present invention, a petroleumresiduum is contacted with the catalyst particles described in thepresence of hydrogen gas at specified values of temperature, pressure,and space velocity. The catalyst particles are usually present in theform of a fixed bed and generally several beds are employed. Thehydrogen gas and residuum are mixed and fed downward through thecatalyst bed. Catalyst bed size and residuum flow rate are adjusted soas to provide a liquid hourly space velocity in the range of about 0.10to 5.0 preferably 0.2-0.8 reciprocal hour. Hydrogen flow rate is fromabout 500 to 5000 standard cubic feet per barrel of oil preferably2000-4000. The reaction temperature is in the range of about 600° toabout 850° F. preferably 650°-750° F. and the total pressure is fromabout 200 to 10,000, preferably 600 to 1000 pounds per square inchguage.

By using the catalyst particles of the present invention in thehydrotreatment of petroleum residuum according to the process described,improved hydrodesulfurization activity compared to prior art catalystsis obtained. In addition, the catalyst particles of the presentinvention exhibit a greater stability of activity on extended use thanprior art catalysts. These results are highly unexpected in view of thefact that prior art teachings indicate that large-pore alumina isrequired to prevent rapid catalyst deactivation in hydrotreating ofpetroleum residuums, which normally contain metallic contaminants. Quitethe contrary to such teachings, the present invention provides greaterstability of catalyst activity in hydrotreating such residuums and, atthe same time, provides a greater activity throughout normal use.

The invention will be more fully understood by reference to theaccompanying drawings in which:

FIG. 1 is a graph comparing the Average Relative Volume Activities ofshaped catalyst particles contemplated by the present invention withconventional catalyst particles of the prior art;

FIG. 2 is a graph comparing the Average Relative Weight Activities ofthe same catalyst particles considered in FIG. 1;

FIG. 3 is a graph comparing the Relative Activities of catalystparticles of the present invention with those of catalyst particles ofthe same composition having conventional configuration, the comparisonsbeing under prescribed conditions;

FIG. 4 is a graph comparing the Average Relative Weight Activities ofcatalyst particles of the present invention with conventional catalystparticles of like composition.

FIG. 5 is a "plate," a convex catalyst not contemplated by thisinvention wherein the dimensions are L=0.186 inch, D=0.094 inch, andd=0.056 inch;

FIG. 6 is a "dumbbell" configuration of this invention wherein thedimensions are L= 0.202 inch, D= 0.0473 inch, l=0.0532 inch and d=0.0264 inch;

FIG. 7 is a dilobal configuration of this invention wherein thedimensions are L= 0.1814 inch, D= 0.092 inch, and d= 0.0541 inch;

FIG. 8 is a three-leaf clover or trilobal configuration of thisinvention wherein the dimensions are L= 0.212 inch, D= 0.0919 inch, d=0.0427 inch, T= 0.0442 inch, and α = 60°;

FIG. 9 is an undimensioned oval convex configuration not contemplated bythis invention;

FIG. 10 is an undimensioned tetralobal configuration of this invention;

FIG. 11 is an undimensioned ring or "donut" configuration contemplatedby this invention;

FIG. 12 represents mercury penetration of catalyst particles in porevolume and the pore size distribution analysis, the larger curvesshowing the complete pore size distribution and the smaller curvesshowing a magnification of the distribution of pore volume in thesmaller pores; and

FIG. 13 is a graph of sulfur removal against time of service use forcatalysts of the present invention and a comparative catalyst inhydrotreating of petroleum residuum.

The invention is more fully illustrated by the examples which followwherein all parts and percentages are by weight unless otherwisespecifically illustrated.

The examples are divided into groups distinguished by either a letter ornumber designation. The lettered examples illustrate catalyst particleuse in hydrotreating processes involving fuel oils while the numberedexamples illustrate catalyst particle use in hydrotreating processesinvolving petroleum residuums. In both groups of examples, advantages inactivity as a result of catalyst shape are shown. In the lettered groupof examples, no specific advantages with respect to pore diameter areapparent so that details as to pore diameter are not presented. In thenumbered groups of examples, where specific advantages result from porediameter, these values are given. Thus, the numbered examples illustratethe conbination of various characteristics of catalyst particles thatconstitute the product aspect of the present invention and illustratehydrotreating of petroleum residuum using the catalyst particles of theinvention, which constitute the process aspect of the present invention.

EXAMPLES A-G

A series of shaped particles were made as follows:

One thousand thirty gallons of water are charged to an agitated tank.3,940 lbs. of sodium aluminate solution (28% Al₂ O₃, about 15% excessNa₂ O) and 5,430 lbs. of aluminum sulfate solution (7.8% Al₂ O₃) aremetered into the water heel and aluminum hydroxide is precipitated.

The pH of the resulting alumina slurry above is adjusted to 10.5 and itis filtered and washed over a rotary vacuum filter to remove thesulfate. Nitric acid is added to the repulped washed cake to adjust thepH down to 7.0-7.5. The pH adjusted slurry is washed over another filterto remove the sodium ions.

The resulting washed slurry above is spray dried.

The spray dried alumina powder (1 Part) is charged to the muller alongwith 1.2 parts of water. Thereafter 0.78 part of ammonium molybdatesolution (28% MoO₃) followed by 0.30 part of cobalt nitrate solution(16% CoO) are added to the mix.

The batch is mixed for a period of about 10-15 minutes, then 0.21 part(ignited basis) of alumina powder is added to the mix, after which thebatch is mulled for an additonal 10-15 minutes.

Using an extruder the muller mix is forced through a die of the desiredshape. The extrudates are dried in an oven to about 20% loss ofignition, and then calcined at a temperature of 1,200° F. for 1 hour.

The above procedure is a procedure used to produce Examples H, I, J andK referred to below. Examples A, B, C, D, E, F, and G, and L and M areprepared in essentially the same manner except that the cobalt nitratesolution and ammonium molybdate solution usage would be adjusted to givea 6% CoO-12% MoO₃ content as opposed to 3% cobalt oxide-15% molybdenumoxide content of Examples H - K. In this series normal "1/16" and "1/8"inch extrudates (cylinders) were made for reference purposes. Thesecatalysts and catalysts of this invention are compared employing thefollowing described Gas Oil Test for desulfurization anddenitrogenation.

GAS OIL TEST GAS OIL DESCRIPTION

Gravity= 23.3° API

Boiling Range= 490°-847° F.

Sulfur Content= 1.0%

Basic Nitrogen Content= 515 ppm

The catalyst is charged into the reactor by volume. Two 25 cc catalystbeds are used in series. Each of these beds is diluted with glass beadsto a total of 100 cc's. The beds are separated with glass wool plug.

The catalyst is then presulfided as follows:

1. The reactor is heater to 600° F. in flowing nitrogen at atmosphericpressure.

2. At 600° F. the nitrogen is stopped and a mixture of 90% H₂ plus 10%H₂ S by volume is passed over the catalyst at 0.85 SCF/hr. for 30minutes.

3. The reactor temperature is then raised to 700° F. and held for 2hours with the H₂ /H₂ S mixture as in 2.

4. After 2 hours the reactor temperature is reduced to 450° F. with H₂/H₂ S flowing. This completes the presulfiding.

The process conditions used are as follows:

Temperature= 650° and 725° F.

Pressure= 750 psig

Space Velocity= 2 LHSV

Hydrogen Recycle Rate= 1,000 SCF/Bbl

Three samples are collected at each temperature. These samples arescrubbed with nitrogen and a portion is then analyzed for basic nitrogenby U.O.P. method 269-59. The remaining portion of the sample is washedwith distilled water three times then analyzed for sulfur. Since this isa diffusion influenced reaction the size of the particle affects itactivity. Results for these two cylinders (1/8 inch and 1/16 inchextrudates) are used to establish the diffusion curve. Activitiesobtained with shaped particles are then compared to the diffusion curveat equal particle size. In order that different shaped particles can bereadily compared, particle size is defined in terms of its volume toexternal surface ratio, Vp/Sp.

In this study two (2) shapes other than cylinders were made. One ofthese has been designated the "dumbbell". The other has been termed a"3-leaf clover" or "trilobe". The particular "dumbbell" is illustratedin FIG. 6 of the accompanying drawings and the particular "trilobe" isillustrated in FIG. 8.

In Table I set forth below activity results for these catalysts areshown. Equal volumes of the catalyst are charged and both sulfur andnitrogen removals are measured at two temperatures as described above.Recent calculations have shown that at both 650° F. and 725° F. thereactor operates in the "trickle" phase (hydrocarbon exists as bothliquid and vapor). In series I (Catalyst A-D) the catalysts werecalcined in a common batch. The Series II catalyst (Catalyst E-G) werecalcined in separate batches. Activity results are displayed in terms ofpercentage removals and relative activities on both a weight and volumebasis. The relative activities are the most meaningful numbers. They aresimply defined as the ratio of second order rate constants (catalystactivity) for the catalyst of interest to that of the referencecatalyst. In each series the 1/16 inch cylinder was the referencecatalyst, i.e. defined to have 100 activity. Relative activities can besimply interpreted as the percentage of activity of the referencecatalyst.

In Series I both the relative weight and volume sulfur activities of theshaped particle are greater than that of the 1/16 inch cylinder. InSeries II, with the exception of one data point which is not believed tobe statistically significant, a similar advantage for sulfur removal isevident. Although the two series do not agree exactly (possibly due todifferences in calcination) their average results show that the shapedparticles have more sulfur removal activity on both a weight and volumebasis.

In Table II, set forth below, the physical properties of the catalystsare given. The significant dimension in terms of generalized particlesize is the Vp/Sp ratio. This ratio shows that the order of increasingsize is: 1/16" Cyl.<dumbbell<trilobe<1/8" cyl. With respect to diffusionthe relative activities should increase with decreasing Vp/Sp. The GasOil Test Results, however, do not correlate with Vp/Sp. Rather, theyshow an unexpected advantage for the shaped particles. If another modeof mass transfer is affecting the results, bulk mass transfer, then onemight expect that the Gas Oil Test results should correlate with totalgeometric surface (total surface in Table II). However the activityresults do not correlate with total surface and again show an unexpectedadvantage for shaped particles. The ABD values show that the dumbbellspack much more loosely than the other particles.

In FIG. 1 of the accompanying drawings the average relative volumeactivities are plotted vs. particle size. The straight line shown is thediffusion curve obtained from the cylinders. It agrees with theory. Boththe dumbbell and the trilobe are above this curve which is a surprisingresult. The dumbell is not as active as the trilobe on this volume basisat least in part because of its low ABD.

A similar graph for weight activities is shown in FIG. 2. Both shapesare significantly above the diffusion curve and have approximately thesame activity.

Finally in Table III pressure drop data are shown for the shapedparticles compared to the 1/16 inch cylinder. Both absolute pressuredrops and relative pressure drops as a function of flow rate are given.In this test 50 cc of catalyst is loaded into a tube and the pressuredrop from flowing air is measured. Both shaped particles of thisinvention show about the same pressure drops and a significant pressuredrop advantage (about 40% lower at the more important flow condition)compared to the 1/16 inch cylinder. For the dumbbell the lower pressuredrop is a direct result of its low ABD. For the trilobe the lowerpressure drop is a result of its increased size (Vp/Sp) and slightlylower ABD.

                                      TABLE I                                     __________________________________________________________________________    GAS OIL TEST ACTIVITY RESULTS                                                                               Relative Activities                             __________________________________________________________________________                    % Removals     Volume Basis   Weight Basis                    __________________________________________________________________________    Catalyst        Sulfur                                                                              Nitrogen                                                                              Sulfur  Nitrogen                                                                              Sulfur  Nitrogen                       Description                                                                            650F                                                                             725F                                                                             650F                                                                              725F                                                                              650F                                                                              725F                                                                              650F                                                                              725F                                                                              650F                                                                              725F                                                                              650F                                                                              725F                __________________________________________________________________________    SERIES I                                                                             "1/16" Cylinder                                                                        85.6                                                                             97.5                                                                              0  30.6                                                                              100 100 --  100 100 100 --  100                 B      Dumbbell 86.8                                                                             98.1                                                                              0  25.2                                                                              111 133 --   79 130 159 --   93                 C      Trilobe  86.3                                                                             97.8                                                                             1.6 33.2                                                                              106 114 --  110 109 117 --  --                  D      "1/8" Cylinder                                                                         71.6                                                                             95.2                                                                             --  --   42  51 --  --   41  49 --  --                  SERIES II                                                                     E      "1/16" Cylinder                                                                        82.2                                                                             97.6                                                                             --  --  100 100 --  --  100 100 --  --                  F      Dumbbell 85.8                                                                             97.2                                                                             --  --  131  85 --  --  159 103 --  --                  G      Trilobe  88.2                                                                             98.5                                                                             --  --  162 161 --  --  164 163 --  --                  AVERAGE I & II                                                                "1/16" Cylinder -- -- --  --  100 100 --  --  100 100 --  --                  Dumbbell        -- -- --  --  121 109 --  --  145 131 --  --                  Trilobe         -- -- --  --  134 137 --  --  137 140 --  --                  "1/8" Cylinder  -- -- --  --   42  51 --  --   41  49 --  --                  __________________________________________________________________________

                                      TABLE II                                    __________________________________________________________________________    PHYSICAL PROPERTIES                                                                                Volume                                                                             Surface   Total                                                          Particle                                                                           Particle  Surface                                   Catalyst   Length                                                                             Dia. Vp   Sp   Vp/Sp                                                                              area PV   ABD CBD CS  CS/L                 Description                                                                             (in) (in) (in).sup.3                                                                         (in).sup.2                                                                         (in) (in).sup.2                                                                         cc/g g/cc                                                                              g/cc                                                                              lbs.                                                                              lbs/in              __________________________________________________________________________    A "1/16" Cylinder                                                                        0.216                                                                              0.052                                                                              0.00046                                                                            0.0398                                                                             0.0117                                                                             176  0.55 0.66                                                                              0.72                                                                              21.5                                                                              101                 B Dumbbell 0.202                                                                              --   0.00096                                                                            0.0798                                                                             0.0121                                                                             124  0.56 0.57                                                                              0.60                                                                              --  --                  C Trilobe  0.212                                                                              --   0.00111                                                                            0.0782                                                                             0.0142                                                                             128  0.57 0.65                                                                              0.69                                                                              31.3                                                                              148                 D "1/8" Cylinder                                                                         0.215                                                                              0.125                                                                              0.00262                                                                            0.1084                                                                             0.0241                                                                             --    .57  .67                                                                               .73                                                                              29  13                  __________________________________________________________________________

                  TABLE III                                                       ______________________________________                                        PRESSURE DROP                                                                 Nomi- A            B            C                                             nal Air                                                                             "1/16" Cylinder                                                                            Dumbbell     3 Leaf Clover                                 Flow  ΔP                                                                              Relative  ΔP                                                                           Relative                                                                             ΔP                                                                            Relative                            SCFM  "H.sub.2 O                                                                            ΔP, %                                                                             "H.sub.2 O                                                                         ΔP, %                                                                          "H.sub.2 O                                                                          ΔP, %                         ______________________________________                                         0;115                                                                              1.5     100      0.94  61     0.98  64                                  1     4.0     100      2.6   64     2.6   64                                  2     15.7    100      11.2  71     11.1  71                                  3     36.4    100      27.0  75     26.3  72                                  ______________________________________                                    

EXAMPLES H-J

Additional examples for shaped catalytic particles are herein reported.A muller mix prepared as described above of a 3% cobalt oxide, 15%molybdenum oxide balance alumina was used to extrude these particles1/16, 1/8" cylinders, dumbbell and trilobe). Activities were obtained ona Heating Oil Test described below:

HEATING OIL TEST HEATING OIL DESCRIPTION

Gravity= 34.2° API.

Boiling Range= 435°-628° F.

Sulfur Content= 1.4%

Basic Nitrogen= 35 ppm

The catalyst is charged to the reactor by volume. Two 25 cc catalystbeds are used in series. Each of these beds is diluted with glass beadsto a total 55 cc's. The beds are separated with a glass wool plug.

The catalyst is then presulfided via the following scheme:

1. The catalyst is heated from room temperature to 700° F. in a mixtureof 10% H₂ S plus 90% H₂ flowing at 5 SCF/Hr. at atmospheric pressure.

2. The catalyst is then held at 700° F. in this mixture for 1 hour.

3. The reactor temperature is then lowered under flowing hydrogen to600° F.

The process conditions used are as follows:

Temperature= 600°, 700° F.

Pressure= 500 psig

Space Velocity= 4 LHSV

Hydrogen Recycle Rate= 1,000 SCF/Bbl

Three samples are collected at each temperature. These samples arescrubbed with caustic:water:caustic and finally water again. They arethen sent for sulfur analysis.

The activity results are shown in Table IV. The results show anadvantage for shaped particles. A graphical presentation of the data isgiven in FIG. 3 for the 700° F. point. Activities for the shapedparticles are above the diffusion curve. Finally, physical properties ofthe catalyst compared are given in Table V.

                                      TABLE IV                                    __________________________________________________________________________    HEATING OIL RESULTS                                                                                     % Relative Activities                                                % Sulfur Removal                                                                       Volume  Weight                                      Catalyst ID                                                                         Description                                                                              600° F.                                                                    700° F.                                                                     600° F.                                                                    700° F.                                                                    600° F.                                                                    700° F.                          __________________________________________________________________________    H     "1/16"  inch cylinder                                                                    46.1                                                                              86.5 100 100 100 100                                     I     Dumbbell   43.0                                                                              87.3  88 107 106 128                                     J     Trilobe    49.6                                                                              88.1 115 116 115 116                                     K     1/8" Cylinder                                                                            44.0                                                                              85.0  92  88  87  83                                     __________________________________________________________________________

                                      TABLE V                                     __________________________________________________________________________    PHYSICAL PROPERTIES                                                                                   Volume                                                                              Surface                                                                 particle                                                                            particle                                                                           Vp                                                         Length                                                                            Dia.                                                                              Vp    Sp   Sp   PV  ABD CBD CS   CS/L                 I.D.                                                                              Description (in.)                                                                             (in.)                                                                             (in.).sup.3                                                                         (in.).sup.2                                                                        (in.)                                                                              cc/g                                                                              g/cc                                                                              g/cc                                                                              lbs. lbs./in.             __________________________________________________________________________    H   "1/16" inch Cylinder                                                                      .142                                                                              .053                                                                              .000316                                                                             .0282                                                                              .0112                                                                              .50 .71 .76 12.3  93                  I   Dumbell     .177                                                                              --  .000838                                                                             .0704                                                                              .0119                                                                              .50 .60 --  --   --                   J   Trilobe     .180                                                                              --  .000933                                                                             .0695                                                                              .0134                                                                              .51 .70 .74 23.3 174                  K   1/8" Cylinder                                                                             .201                                                                              .115                                                                              .00209                                                                              .0934                                                                              .0224                                                                              .51 .74 .78 27.7 223                  __________________________________________________________________________

                                      TABLE VI                                    __________________________________________________________________________    GAS OIL TEST ACTIVITY RESULTS                                                                   % Relative Activities                                       Catalyst % Sulfur Removal                                                                       Volume                                                                              Weight                                                                              Vp/Sp                                                                             Concavity                                   I.D.                                                                             Description                                                                         650F 725F                                                                              650F                                                                             725F                                                                             650F                                                                             725F                                                                             in. C                                           __________________________________________________________________________    L  Dilobe                                                                              66.2 97.8                                                                              117                                                                              112                                                                              120                                                                              115                                                                              .0139                                                                             1.04                                        M  Flat Plate                                                                          85.3 96.9                                                                              110                                                                               78                                                                              104                                                                               74                                                                              .0154                                                                             1.00                                        __________________________________________________________________________

                                      TABLE VII                                   __________________________________________________________________________    PHYSICAL PROPERTIES                                                                       Length                                                                            Dia.                                                                             Vp   Sp  Vp/Sp                                                                             PV  ABD                                                                             CBD                                                                              CS CS/L                              I.D.                                                                             Description                                                                            (in.)                                                                             (in.)                                                                            (in).sup.3                                                                         (in).sup.2                                                                        in. cc/g                                                                              g/cc                                                                            g/cc                                                                             lbs.                                                                             lbs./in.                          __________________________________________________________________________    L  Dilobe                                                                        (FIG. 6 Drawings)                                                                      .181                                                                              -- .000756                                                                            .0544                                                                             .0139                                                                             .55                                                                              .64                                                                              .71                                                                              52 415                               M  Flat Plate                                                                    (FIG. 5 Drawings)                                                                      .187                                                                              -- .000874                                                                            .0567                                                                             .0154                                                                             .56                                                                              .68                                                                              .72                                                                              57 455                               __________________________________________________________________________

EXAMPLES L-M

Using the same catalyst material as was used in Examples A-G and thesame test, these catalysts were rotary calcined as were the Series IIcatalysts in Table I hereinbefore.

The shapes studied were a dilobe with a small amount of concavity,C=1.04, and a flat plate which is convex, C=1.00, but with a noncircularcross section. These results are shown in Table VI. The average resultsfrom catalyst A and catalyst C were used to calculate the relativeactivities in Table VI. To simplify the data interpretation the averagerelative weight activities (650° F., and 725° F.) are plotted as afunction of particle size in FIG. 4. In general those particles with aconcavity index, C, equal to 1.00 fall on the diffusion curve. Thedilobe with C=1.04 falls above the diffusion curve but not as high asthose with C=1.10 or greater. These data tend to support the hypothesisthat C must be greater than 1.00. FIG. 4 demonstrates that. Preferably,C should be in the neighborhood of 1.10.

It will be apparent that the above described invention and parametersrelate to freshly prepared catalyst particles of unique size and shapeand does not contemplate conventional catalyst shapes and size havingimperfection therein of the type that may be described as knicks, chips,abrasions, bends and the like.

In Examples A-M, inclusive, the advantages in activity in processing gasoils is apparent for catalysts of unique shape. In hydrotreating gasoils, however, a wide range of average pore diameter in the catalystmaterial may be used effectively, i.e., the activity values appear to beinfluenced by the shape factor apart from any influence resulting fromaverage pore diameter. This is apparently due to the fact that the gasoils have a relatively low boiling range, reflecting low molecularweight of components, and are essentially free from metallic components.

In the numerical examples which follow, hydrotreating is effected onpetroleum residuums, which contain metallic contaminants and have ahigher boiling range than gas oils, reflecting relatively highermolecular weight components than in gas oil. These properties of thefeedstock processed have been held to influence the specific averagepore diameter of catalysts that can effectively be employed. Therefore,in the numerical examples the average pore diameter values are given.

EXAMPLE 1

An alumina was precipitated over a heel of silica hydrogel. Theresulting precipitate was washed free of salts. Ammonium heptamoylbdate[(NH₄)₆ MO₇ O₂₄ ] and water were added to the washed aqueous slurry andthe mixture was spray dried.

To (1 part) of the spray dried powder was added 1 part of water and 0.33part of concentrated HNO₃. The ingredients were mixed together and thenextruded using a die containing orifices in the "trilobe" shape. Theextrudates were dried at 120° C. for 16 hours and then calcined at 650°C. for 1 hour.

An 800 gram portion of the calcined extrudates was impregnated with anaqueous solution at 136 grams Co(NO₃)₂. 6H₂ O and 53 grams urea. Theimpregnated extrudates were dried at 120° C. for 16 hours and thencalcined at 650° C. for 1 hour.

Extrudate properties are given in Table VIII, porosity in FIG. 12, andactivity in FIG. 13.

EXAMPLE 2

The procedure of Example 1 was followed in every material detail exceptthat drying and calcining of the extrudate was carried out in thepresence of a positive air flow by placing a vacuum line beneath thecatalyst particles

                  TABLE VIII                                                      ______________________________________                                        SHAPED EXTRUDATE PROPERTIES                                                                   Example  Example  Comparative                                 Property        1        2        Example I                                   Pore Volume (H.sub.2 O) ml.                                                                   0.49     0.47     0.76                                        Pore Volume (Hg)* ml.                                                                         0.45     0.41     0.75                                        Surface Area (N.sub.2) m.sup.2 /gm                                                            237      --       211                                         Surface Area (Hg)* m.sup.2 /gm                                                                243      254      195                                         Mean Pope Diameter                                                                            68       54       146                                         (Hg)* A°                                                               Compacted Bulk Density g./l                                                                   .76      .80      .55                                         Particle Length (inch)                                                                        0.114    0.135    0.12                                        Maximum Diameter (D)                                                                          0.51     0.51     0.53                                        (inch)                                                                        Composition Weight Percent                                                    CoO             4        4        4                                           MoO.sub.3       12       12       12                                          SiO.sub.2       2        2        2                                           Al.sub.2 O.sub.3                                                                              Balance  Balance  Balance                                     ______________________________________                                         *140° Contact Angle   placed in a rack. The air flow was employed      in the drying and calcining steps prior to and subsequent to impregnation.

Extrudate properties are also given in Table VIII and FIGS. 12 and 13.

Comparative Example I

A spray dried precipitated alumina was prepared according toconventional procedures. To 1 part of the alumina was added 0.25 part ofsilica hydrogel of 7.2% calcined solids, 0.14 part of Co(NO₃)₂.6H₂ O,0.13 parts of (NH)₄ MO₇ O₂₄.XH₂ O, 0.05 part urea, 0.7 part water, 0.075part ammonia hydroxide (28% NH₃), and 0.009 part of Superfloc (a highmolecular weight polyacrylamide). The components were mixed together andextruded as "trilobe" extrudates. The extrudates were dried at 120° C.for 16 hours and calcined at 650° C. for 1 hour.

Extrudate properties are also given in Table VIII and FIGS. 12 and 13.

In Table VIII, it can be seen that the major differences in catalysts ofthe present invention and that of the prior art (Comparative Example I)are the total pore volume, mean pore diameter, and compacted bulkdensity, the latter property being influenced by total pore volume.

In FIG. 12, the specific distribution of pore diameters in the catalystmaterials can be seen and it can be readily appreciated that themajority of pores of catalysts of the present invention are within anarrow range of diameters in the range of 40-90 A units as measured.

In order to evaluate the catalysts for activity over an extended timeperiod, the following test procedure was employed.

A suitable reactor was employed which contains two fixed beds in serieseach of a volume of 100 millimeters. In the case of the catalysts ofExample 1 and Comparative Example I, the beds were each filled with 50milliliters of catalyst and 50 milliliters of glass beads intimatelymixed. In the case of the catalyst of Example 2, the beds were eachfilled with 100 milliliters of catalyst alone.

The catalysts were pretreated in a nitrogen atmosphere at 600° F. andthen contacted with a gaseous mixture of 90 mole percent H₂ and 10 molepercent H₂ S at 600°-700° F. for 2 hours at an absolute pressure of 50pounds per square inch.

In the hydrotreating reaction, a residuum feedstock of the followingproperties were employed:

    ______________________________________                                        Kuwait Atmos. Resid.                                                          Gravity ° API 22.4                                                     Sulfur Weight Percent                                                                               3.6                                                     Metal Parts Per Million                                                       V                    45                                                       Ni                   12                                                       Na                   10                                                       Basic N              289.                                                     ______________________________________                                    

Hydrogen gas and the resid were mixed together and fed into the top ofthe reactor. The conditions maintained during reaction were as follows:

    ______________________________________                                        Temperature       725° F.                                              Liquid Hourly Spaced Velocity                                                                   0.5 reciprocal hr.                                          H.sub.2 addition rate                                                                           1000 SCF/barrel Oil                                         Total Pressure    800 pounds/inch.sup.2 gauge                                 ______________________________________                                    

After various time intervals of reaction, the percent sulfur removal wasdetermined and the data plotted as a function of time of operation. Inthe case of Example 1, duplicate runs were made. The results are shownin FIG. 13.

From FIG. 13, it can be readily seen that sulfur removal is greater fora catalyst of the present invention than for the prior art catalyst. Itcan also be seen that as the time of use for a catalyst increases, theprior art catalysts shows a much greater loss in activity than does acatalyst of the present invention.

EXAMPLE 3

In order to illustrate the unexpected crush strength properties ofcatalyst particles of the present invention, the crush strength valuesof individual particles were divided by the ratio of geometric volume togeometric surface of the individual particles, this ratio indicating theactual particle size. Thus, the result of such division indicates thestrength of the particle as a function of its particle size. The resultsare given in TABLE IX, which follows.

                  TABLE X                                                         ______________________________________                                        Crush Strength vs. Particle Size                                                                                 Crush                                                                  Crush  Strength                                           Catalyst    Vp/Sp   Strength                                                                             Vp/Sp                                      Catalyst                                                                              Shape       Inch    (lbs.) (lbs.in.)                                  ______________________________________                                        A       1/16" cylinder                                                                            0.0117  21.5   1840                                       C       Trilobe     0.0142  31.3   2210                                       D       1/8" cylinder                                                                             0.0241  29.0   1205                                       H       1/16" cylinder                                                                            0.0112  12.3   1100                                       J       Trilobe     0.0134  23.3   1740                                       K       1/8" Cylinder                                                                             0.0224  27.7   1235                                       ______________________________________                                    

The results in TABLE IX show that the trilobal shaped catalyst of thepresent invention has a greater crush strength than would be expectedfrom its particle size. The differences in values associated withCatalysts, A, C, and D and Catalysts H, J, and K result from differencesin calcination conditions in preparing the catalysts, but the higherparticle strength of catalysts of the invention is evident under eithercondition of calcination.

It is to be noted that attrition or abrasion, resistance of catalystparticles is influenced by their crush strength, better resistance beinggenerally obtained at higher crush strength values.

It is also to be noted that particle strength and particle integrity arenot necessarily the same. In measuring particle strength, the particleis crushed to a powder. However, the specific cross-sectional shape of aparticle may be ruptured well before the crushing force necessary topulverize the particle is reached. Thus, when the cross-sectional shapeis such as to contain extensive arms, such as in the clover-leaf shapeof U.S. Pat. No. 3,674,680, the arms are ruptured at crush strengthvalues well below that necessary to pulverize the particle. Catalysts ofthe present invention, however, have particle integrity that issubstantially equivalent to particle strength.

I claim:
 1. A process for hydrotreating a petroleum residuum with aporous hydrotreating catalyst particle to obtain a desulfurized product,said particle having a composition of a major portion of alumina; up toabout 36 weight percent of silica, based on the total weight of silicaand alumina; from about 10 to 25 weight percent of molybdenum in theform of its oxide or sulfide; and a total of about 1 to 8 weight percentof a metal selected from cobalt, nickel, and mixtures thereof in theform of the corresponding oxide or sulfide, said percentages being basedon the total weight of said catalyst particle; said particle beingfurther characterized by a polylobal cross-sectional shape defining aconcave geometric solid, said cross-sectional shape being defined bycircles, all of said circles being spaced from one another by a distancewhich is from three-eighths to about fifteen-sixteenths of the diametersof said circles and when more than two lobes are present, linesconnecting the centers of adjacent circles form a substantiallyequilateral polygon, each side of said polygon being from three-eighthsto fifteen-sixteenths of the diameter of said circles and all of saidcross-sectional shape included by said circles being of saidcomposition; said particle size being defined by a ratio of geometricvolume to geometric surface in the range of about 0.001 to 0.042 inch; acatalytic surface area greater than 150 square meters per gram; and acatalytic pore volume in the range of about 0.35 to 0.85 cubiccentimeters per gram, said pore volume resulting from a major portion ofpores of diameter in the range of 40 to 90 Angstrom units when measuredwith mercury at up to about 50,000 pounds per square inch absolutepressure and a contact angle of 140°; which process comprises contactingsaid residuum with said catalyst particle and with hydrogen at a flowrate of about 500 to 5,000 standard cubic feed per barrel of oil at aliquid hourly space velocity of about 0.20 to 5.0 reciprocal hour, atemperature in the range of about 600° to 850° F., and a total pressurein the range of about 200 to 10,000 pounds per square inch guage.
 2. Theprocess of claim 1 wherein the hydrogen flow rate is 2,000 to 4,000standard cubic feet per barrel of residuum.
 3. The process of claim 1wherein the liquid hourly space velocity is 0.2-0.8 reciprocal hour. 4.The process of claim 1 wherein the temperature is 650°-750° F.
 5. Theprocess of claim 1 wherein the total pressure is 600-2000 pounds persquare inch gauge.
 6. The process of claim 1 wherein the hydrogen flowrate is 1,000 standard cubic feet per barrel of oil the liquid hourlyspace velocity is 0.5 reciprocal hour, the temperature is 725° F., andthe total pressure is 800 pounds per square inch gauge.
 7. A process forhydrotreating a petroleum residuum with a porous hydrotreating catalystparticle to obtain a desulfurized product, said particle having acomposition comprising a major portion of alumina; up to about 36 weightpercent of silica, based on the total weight of silica and alumina; fromabout 10 to 25 weight percent of molybdenum in the form of its oxide orsulfide; and a total of about 1 to 8 weight percent of a metal selectedfrom cobalt, nickel and mixtures thereof in the form of thecorresponding oxide or sulfide, said percentages being based on thetotal weight of said catalyst particle, said particle being furthercharacterized by a trilobal cross-sectional shape defining a concavegeometric solid, said trilobal cross-sectional shape being defined bycircles, all of said circles in said cross-sectional shape having equaldiameters, the centers of said circles being spaced from one another bya distance which is from about three-eighths to fifteen-sixteenths ofthe diameters of said circles, lines connecting the centers of adjacentcircles form a substantially equilateral triangle, each side of saidtriangle being from three-eighths to fifteen-sixteenths of the diametersof said circles and all of the cross-sectional shape included by saidcircles being of said composition; said particle size being defined by aratio of geometric volume to geometric surface in the range of about0.005 to 0.025 inch; a catalytic surface area greater than 200 squaremeters per gram; and a catalytic pore volume in the range of about 0.45to 0.85 cubic centimeters per gram, said catalytic pore volume resultingfrom a major portion of pores of diameter of about 40 to 90 Angstromunits when measured with mercury at up to about 50,000 pounds per squareinch absolute pressure and a contact angle of 140°; which processcomprises contacting said residuum with said catalyst particle and withhydrogen at a flow rate of about 500 to 5,000 standard cubic feet perbarrel of oil at a liquid hourly space velocity of about 0.20 to 5.0reciprocal hour, at a temperature in the range of about 600° to 850° F.,and a total pressure in the range of about 200 to 10,000 pounds persquare inch gauge.